Clinical characteristics and predictors of in-hospital mortality in patients with ANCA-associated vasculitis complicated by diffuse alveolar hemorrhage: a retrospective cohort study

Background Diffuse alveolar hemorrhage (DAH) is a life-threatening manifestation of ANCA-associated vasculitis (AAV). Data regarding the determinants of in-hospital mortality, particularly the role of specific opportunistic pathogens, remain limited. Study design and methods This retrospective cohort study included patients with AAV complicated by DAH admitted to Peking University First Hospital between January 2015 and December 2025. Clinical characteristics, bronchoalveolar lavage fluid (BALF) profiles, microbiological findings, and therapeutic interventions were compared between survivors and non-survivors. Candidate predictors were selected a priori based on clinical relevance and published evidence. Least absolute shrinkage and selection operator (LASSO) regression was employed as a complementary screening tool, and multivariable logistic regression was performed to identify independent risk factors for in-hospital mortality. Results A total of 58 patients were enrolled, of whom 13 (22.4%) died during hospitalization. Infection-related septic shock was the predominant cause of death, accounting for 76.9% of fatalities. Pulmonary infection occurred in 60.3% of the cohort and was significantly more frequent among non-survivors (92.3% vs. 51.1%; p = 0.009). Invasive pulmonary aspergillosis (IPA) was identified in 12.1% of all patients and was markedly more common in non-survivors (46.2% vs. 2.2%; p < 0.001). On multivariable analysis, a higher baseline age-adjusted Charlson Comorbidity Index (aCCI) (adjusted OR, 2.78; 95% CI, 1.31–5.87; p = 0.007) and the need for early mechanical ventilation (adjusted OR, 14.45; 95% CI, 1.17–179.11; p = 0.038) remained independently associated with in-hospital mortality. Conclusion Among patients with AAV complicated by DAH, in-hospital mortality remains substantial and is predominantly attributable to infection-related septic shock. Higher baseline aCCI and the need for early mechanical ventilation are independent predictors of in-hospital death. The high incidence of IPA may be associated with mortality and underscores the need for heightened clinical vigilance and proactive screening in this profoundly immunocompromised population.